| 1. |
- Braian, Michael, et al.
(författare)
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Trueness and precision of 5 intraoral scanners for scanning edentulous and dentate complete-arch mandibular casts: A comparative in vitro study
- 2019
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Ingår i: Journal of Prosthetic Dentistry. - : Elsevier BV. - 0022-3913 .- 1097-6841. ; 122:2, s. 129-136
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Tidskriftsartikel (refereegranskat)abstract
- Statement of problem. Limited information is available on the trueness and precision of intraoral scanners (IOSs) for scanning dentate and edentulous casts. Purpose. The purpose of this in vitro study was to evaluate the trueness and precision of 5 different IOS devices for scanning a dentate and an edentulous cast in a standardized way for short arches and complete arches. Material and methods. Five IOS devices were used to scan 2 computer metric measured casts using a coordinate measuring machine (CMM). Both were scanned 15 times. All scans were carried out by 1 experienced operator in a standardized way. One cast was edentulous, and 1 was dentate. Five cylindrical landmarks were added to each cast. These cylinders made the measurement of point-to-point distances possible, dividing the tests into cross-arch measurements and intercylindrical (short-arch) measurements. The Student t test, Mann-Whitney test, and Levene test for equality were used to calculate the difference between the edentulous and dentate scans for both cross-arch and intercylindrical measurements (alpha=.05). Results. For the cross-arch measurements on the edentulous scans, the trueness values ranged between 6 mu m (Emerald P1-P2) and 193 mu m (Omnicam P1-P5) and for the intercylindrical measurements, between 2 mu m (Itero P4-P5) and -103 mu m (CS 3600 P1-P2). For the dentate cast, the cross-arch trueness values ranged between 6 mu m (CS 3600 P1-P2) and 150 mu m (TRIOS 3 P1-P5) and for the intercylindrical measurements, between 4 mu m (Itero P4-P5) and -56 mu m (Emerald P4-P5). Conclusions. Significant differences were found in scanning edentulous and dentate scans for short arches and complete arches. Trueness for complete-arch scans were <193 mu m for edentulous scans and <150 mu m for dentate scans. Trueness for short-arch scans were <103 mu m for edentulous scans and <56 mu m for dentate scans.
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| 2. |
- Gjelvold, Björn, et al.
(författare)
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Accuracy of surgical guides from 2 different desktop 3D printers for computed tomography-guided surgery
- 2019
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Ingår i: The Journal of prosthetic dentistry (Print). - : Elsevier. - 0022-3913 .- 1097-6841. ; 121:3, s. 498-503
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Tidskriftsartikel (refereegranskat)abstract
- STATEMENT OF PROBLEM: Different factors influence the degree of deviation in dental implant position after computed tomography-guided surgery. The surgical guide-manufacturing process with desktop 3D printers is such a factor, but its accuracy has not been fully evaluated.PURPOSE: The purpose of this in vitro study was to evaluate the deviation in final dental implant position after the use of surgical guides fabricated from 2 different desktop 3D printers using a digital workflow.MATERIAL AND METHODS: Twenty 3D-printed resin models were prepared with missing maxillary premolar. After preoperative planning, 10 surgical guides were produced with a stereolithography printer and 10 with a digital light-processing (DLP) printer. A guided surgery was performed; 20 dental implants (3.8×12 mm) were installed, and a digital scan of the dental implants was made. Deviations between the planned and final position of the dental implants were evaluated for both the groups.RESULTS: A statistically significant difference between stereolithography and DLP were found for deviation at entry point (P=.023) and the vertical implant position (P=.009). Overall lower deviations were found for the guides from the DLP printer, with the exception of deviation in horizontal implant position.CONCLUSIONS: The tested desktop 3D printers were able to produce surgical guides with similar deviations with regard to the final dental implant position, but the DLP printer proved more accurate concerning deviations at entry point and vertical implant position.
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| 3. |
- Lövgren, Niklas, et al.
(författare)
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Effect of production method on surface roughness, marginal and internal fit, and retention of cobalt-chromium single crowns
- 2017
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Ingår i: The Journal of prosthetic dentistry (Print). - : Elsevier. - 0022-3913 .- 1097-6841. ; 118:1, s. 95-101
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Tidskriftsartikel (refereegranskat)abstract
- STATEMENT OF PROBLEM: New production methods have been developed for metal ceramic restorations. Different production methods may show different surface roughness and fit, which may affect retention and long-term success. PURPOSE: The purpose of this in vitro study was to examine 3 different production methods with regard to surface roughness, marginal and internal fit, and retention of cobalt-chromium alloy single-crown copings. MATERIAL AND METHODS: A master abutment of a premolar mandibular tooth preparation with 4-mm height and a 0.6-mm deep 120-degree chamfer finish line with a 12-degree angle of convergence was replicated in die stone and scanned. Thirty-six cobalt-chromium alloy copings were produced using 3 different production techniques. Twelve copings were produced by laser-sintering, 12 by milling, and 12 by milled wax/lost wax. The surface microstructure of 2 copings in each group was analyzed using interferometry. The remaining 10 copings in each group were used to evaluate marginal and internal fit by using an impression material replica method, and retention was evaluated by using a uniaxial tensile force pull-off test. The copings from each test group were cemented with zinc phosphate cement onto resin abutments. Statistical analyses of differences in marginal and internal fit were performed using 1-way ANOVA and the Mann-Whitney U test. Differences in surface topography were analyzed with the Kruskal-Wallis and Mann-Whitney U tests for nonparametric data. Differences in retentive values were analyzed using the Mann-Whitney U test for nonparametric data (all α=.05). RESULTS: Differences in surface microstructure were seen. The laser-sintered copings showed increased surface roughness compared with milled and milled wax/lost wax copings. Differences in marginal and internal fit were noted. Laser-sintered showed significantly smaller spaces between coping and abutment than milled wax/lost wax copings (P=.003). At the margins, laser-sintered copings showed significantly smaller spaces than either the milled wax/lost wax group (P=.002) or the milled group (P=.002). At the chamfer, laser-sintered copings showed significantly smaller spaces than milled wax/lost wax copings (P=.005). At the center of the axial walls, laser-sintered copings showed significantly smaller spaces than those in the milled wax/lost wax (P=.004) and milled copings (P=.005). No significant differences were noted between milled and milled wax/lost wax copings (P>.05). No significant differences were detected regarding retentive forces in the pull-off tests (P>.05). CONCLUSIONS: Laser-sintered Co-Cr crown copings showed increased surface roughness and better internal and marginal fit than copings produced by milling or milled wax/lost wax technique. However, the crown pull-off tests did not reveal any significant differences.
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| 4. |
- Matthys, Carine, et al.
(författare)
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Impact of crestal bone resorption on quality of life and professional maintenance with conventional dentures or locator-retained mandibular implant overdentures
- 2018
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Ingår i: The Journal of prosthetic dentistry (Print). - : Elsevier. - 0022-3913 .- 1097-6841. ; 120:6, s. 886-894
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Tidskriftsartikel (refereegranskat)abstract
- STATEMENT OF PROBLEM: The influence of the mandibular resorption profile on clinical outcome after converting a conventional complete denture into a Locator-retained implant overdenture is unknown. PURPOSE: The purpose of this prospective study was to assess the oral health-related quality of life (OHRQoL) and prosthetic maintenance of mandibular overdentures on 2 Locator abutments in relation to the resorption degree of the edentulous mandible. MATERIAL AND METHODS: Twenty-five participants were treated and classified according to the Cawood and Howell (CAW-H) resorption classification for the resorption profile of the mandible, CAW-H group III-IV (n=14) and CAW-H group V (n=11). Participants received conventional complete dentures (CDs) before implant placement and immediate nonfunctional loading on locators with a resilient liner. After 3 months, the attachments were functionally activated. Assessments were made using the Oral Health Impact Profile 14 (OHIP-14) questionnaires with existing CDs and new CDs at 1, 3, and 15 months after loading. Prosthetic maintenance (repairs, rebasings, replacement of retention parts) and biological prosthetic aftercare were assessed. For comparison between groups, the Kruskal-Wallis and Mann-Whitney U tests were applied for continuous and ordinal variables and the chi-square test for cross-tabulations. To analyze repeated OHIP-14 scores, the Friedman test was used for ordered alternatives to test whether the measurements differed (overall significance level alpha=.05). Then the Wilcoxon signed rank test was conducted to detect specific differences (alpha=.05). RESULTS: OHIP-14 scores decreased significantly after implant placement and functional connection for the whole population (P<.001) and for both sub groups, the CAW-H group III-IV (P<.001) and the CAW-H group V (P=.013). CAW-H group V participants needed more retention inserts than CAW-H group III-IV participants (26 versus 3, respectively; P=.006). The incidence of repair and rebasing was limited for both groups, and biological aftercare and pain relief were comparable. CONCLUSIONS: Changing a CD to an overdenture significantly improved ORLQoL regardless of the resorption degree, but heavily resorbed mandibles require more replacements of retention inserts.
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| 5. |
- Rayyan, Mohammad M., et al.
(författare)
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Comparison of interim restorations fabricated by CAD/CAM with those fabricated manually
- 2015
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Ingår i: The Journal of prosthetic dentistry (Print). - : Mosby. - 0022-3913 .- 1097-6841. ; 114:3, s. 414-419
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Tidskriftsartikel (refereegranskat)abstract
- Statement of problem. Interim restorations represent an essential treatment step; however, the optimal resin material for long-term interim restorations requires investigation. Purpose. The purpose of this in vitro study was to compare the color stability, water sorption, wear resistance, surface hardness, fracture resistance, and microleakage of computer-aided design/computer-aided manufacturing-(CAD/CAM) fabricated interim restorations with those of manually fabricated interim restorations. Material and methods. Epoxy replicas were made from a prepared maxillary first premolar. On the replicas, interim crowns were fabricated and divided into the following groups: CAD/CAM poly(methyl methacrylate) (PMMA) blocks (CC), autopolymerizing temporary resin (AP), automix temporary resin (AM), and thermoplastic resin (TP). After cementation, all specimens were subjected to thermocycling and dynamic fatigue. The CIE Laboratory color coordinates were then recorded before and after immersion in coffee, tea, carbonated cola, and red wine. Water sorption was evaluated by using an immersion technique. Wear resistance was measured in a surface abrasion device. Vickers microhardness was measured on polished specimens. Fracture resistance was evaluated by axial loading with a universal testing machine. Marginal dye penetration was evaluated by sectioning the interim restorations after immersion in methylene blue (alpha=.05). Results. Colorimetric analysis revealed a large degree of color alteration (SE) in the manually fabricated interim restorations: AP = Delta E of 6.7 +/- 2); AM = Delta E of 7.1 +/- 1.5), and TP = Delta E of =5.4 +/- 3.1. The CC group demonstrated color stability (Delta E=2.1 +/- 0.2). CAD/CAM interim restorations demonstrated significantly lower water sorption, higher wear resistance, higher surface hardness, and significantly higher fracture resistance (1 289 +/- 56N) compared with manually fabricated interim restorations (AP=996 +/- 45, AM=899 +/- 37, and TP=1179 +/- 41). The stereomicroscopic examination of sectioned specimens demonstrated the absence of dye penetration in all tested specimens. Conclusions. CAD/CAM interim crowns presented stable physical and mechanical properties and may be used for long-term interim restorations.
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| 6. |
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| 7. |
- Svanborg, Per, 1978, et al.
(författare)
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Fit of 3Y-TZP complete-arch implant-supported fixed dental prostheses before and after porcelain veneering
- 2019
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Ingår i: The Journal of prosthetic dentistry (Print). - : Elsevier. - 0022-3913 .- 1097-6841. ; 122:2, s. 137-141
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Tidskriftsartikel (refereegranskat)abstract
- STATEMENT OF PROBLEM: To minimize technical complications, implant-supported fixed dental prostheses must fit well. The fit of complete-arch veneered zirconia frameworks has not been fully evaluated.PURPOSE: The purpose of this in vitro study was to evaluate the fit of screw-retained zirconia implant-supported complete-arch maxillary frameworks for fixed dental prostheses before and after porcelain veneering.MATERIAL AND METHODS: Ten stone casts simulating an edentulous maxilla and provided with 6 abutment analogs were produced. For each stone cast, 1 zirconia framework was fabricated by computer-aided design and computer-aided manufacturing. The fit was analyzed by using a coordinate measuring machine in 3 dimensions (x, y, and z axes) using best fit by virtual matching of center point coordinates before and after porcelain veneering. Also, the horizontal distances between implant position pairs P1-P6, P2-P5, and P3-P4 were measured. Furthermore, an optical microscope was used to evaluate vertical fit at the terminal abutments after porcelain veneering.RESULTS: Before the porcelain veneering procedure, the frameworks had a mean horizontal misfit of 27.7 μm in the x-axis and 12.0 μm in the y-axis. In the vertical dimension (z-axis), the mean misfit was 2.4 μm and the mean 3D misfit value was 32.3 μm before veneering. Porcelain veneering increased the mean misfit by 0.2 μm in the horizontal plane (x and y axes), 0.4 μm in the vertical plane, and 0.4 μm in 3D; the difference before and after veneering was not statistically significant (P>.05). The mean ±standard deviation vertical misfit at the terminal abutments was 9.2 ±2.9 μm, optically recorded after porcelain veneering. The measured horizontal distances between implant position pairs P1-P6, P2-P5, and P3-P4 increased to 0.9 μm, 2.0 μm, and 1.9 μm, respectively, after porcelain veneering. The difference for the implant position pair P2-P5 was statistically significant (P<.05).CONCLUSIONS: Screw-retained zirconia implant-supported complete-arch maxillary frameworks for fixed dental prostheses have a fit well within the range of 30 μm in the horizontal plane and 10 μm in the vertical plane. The porcelain veneering procedure did not affect the fit of the frameworks.
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